Generally, diabetes is one of complex metabolic diseases that cause lesions in microvessels, resulting in wide disorders in systemic tissues including eyes, especially the most important one of the systemic diseases affecting eyes (Lee, TaeHee, Choi, YoungGil. Diabetic vascular complications, Seoul: Korean Medical Book Publisher (1993)). Amongst them, the diabetic retinopathy belong to one of the most severe complications, and has become social problems since improved lifestyles and advanced medical standards make the life expectance and the morbid period of diabetics longer (Klein R. et al, Arch Opthalmol. 102:520-532 (1984)). The diabetic retinopathy is divided into two groups: a non-proliferative diabetic retinopathy in which retinal lesions caused by vascular disorders are defined within the retina, and a proliferative diabetic retinopathy in which neovascular tissues infiltrate from the retina into a vitreous cavity (Green, In: Spencer WH, ed. Ophthalmic Pathology: an atlas and textbook. 4th ed. Philadelphia: WB Saunder; 1124-1129 (1996)). The diabetic retinopathy is diagnosed by characteristic structural changes in the fundus. Loss of eyesight due to the diabetic retinopathy results from vitreous hemorrhages and macular degeneration together with traction retinal detachment of a macula lutea in the proliferative diabetic retinopathy, and they may be effectively treated using laser treatments along with surgeries (Diabetic Retinopathy Study Report Number 14: Int Opthalmol Clin. 27:239-253 (1987)). Such a treatment may be undergone at a suitable stage to minimize side effects of the diabetic retinopathy and prevent loss of eyesight. Accordingly, medical examinations of the diabetic retinopathy and careful diagnoses should be often conducted to determine whether or not surgeries are operated. However, only an examination by means of fundus photography has been currently conducted in ophthalmic hospitals as the diagnosis method, and therefore it is difficult to diagnose the diabetic retinopathy at an early stage, and prevention and surgical operation times may be frequently missed.
An ability to detect changes in a DNA sequence is necessarily required for determining molecular basis of hereditary diseases and specifying polymorphisms and so on of genetics. Detection and diagnosis of hereditary mutations at a DNA level have been carried out using karyotyping, restriction fragment length polymorphisms (RFLPs) or variable nucleotide type polymorphisms (VNTRs), etc., and a single nucleotide polymorphism (SNP) method has recently been widely used.
It has been found that a certain SNP difference between VEGF, which is directly relevant to inducing the diabetic retinopathy, and VEGF receptor genes (IOVS 2001 42,10 pp 2408-13) is related to the diabetic retinopathy, and the said methods are used for diagnosing a high risk group to contribute to its prevention and treatment.